Embodiments in accordance with the present invention relate to disk units, magnetic disk units and information storage units such as hard disk drive units.
Disk units including hard disk drive units are being used in a wide variety of fields. In recent years, particularly, hard disk drive units are being used in various information processing systems as represented by personal computers. Such hard disk drive units allow a user to record content including movies and music and play the content recorded in the hard disk drive unit in advance.
In the case where a hard disk drive unit in which content is stored is lent at a rental agency, a lender requests to prevent illegal actions from being taken by a borrower. The above illegal actions include storing other content in the hard disk drive unit and deleting the content pre-stored in the hard disk drive unit. In addition, the lender requests to prevent the hard disk drive unit from being accessed by a third party other than the borrower without any permission.
In addition, in the case where confidential information is leaked from the hard disk drive unit due to illegal access to an information processing system, it is requested to prevent records such as access logs from being falsified. Otherwise, it is not possible to legally clarify the illegal access.
Further, in a system where images from a security video camera are recorded in a hard disk drive unit, there is a request for limiting users who can access the images (recorded data) for private information protection.
In the above-mentioned conventional technique, however, these requests cannot be accomplished since the hard disk drive unit allows a plurality of operation modes to be performed. The operation modes include recording content therein, playing content therefrom and recording content while playing it.